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(CNN)The U.S. launched a new ground-based missile defense system in Romania Thursday, sparking fresh tensions with Russia, which quickly blasted the system as a threat to its security.

The system, to be operated by NATO, is getting up and running nearly a decade after the U.S. first announced plans to do so, only to encounter pushback from Russia. The U.S. has long insisted that the shield is directed against rogue states like Iran and not intended to target Moscow's missiles, but Russian officials have slammed the move as an "attempt to destroy the strategic balance" in Europe.

"The United States' Aegis ashore system is declared certified for operations," NATO Secretary General Jens Stoltenberg said Thursday at the ceremony launching the system.

"Missile defense is for defense," he added. "It does not undermine or weaken Russia's strategic nuclear deterrent."

Russia has described the U.S. anti-missile shield in Europe as a "threat" and says it is taking "protective measures" to guard against it, the country's state news agency TASS reported.

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President Barack Obama scrapped the George W. Bush administration's planned bilateral deployment of a different system to Poland and the Czech Republic and has instead pursued a NATO-centric approach using alternate technology.

The system is to be turned over to NATO command and will be housed at a U.S. naval support facility in Deveselu, Romania, the site of a Romanian military base. Construction will begin on an additional anti-missile platform in Poland on Friday.

The Aegis Ashore Missile Defense System unveiled Thursday is capable of firing SM-3 defensive missiles that can "defeat incoming short and medium range enemy missiles," according to Lt. Shawn Eklund, a spokesman for the U.S. Navy.

Eklund told CNN that the facility will be manned by approximately 130 U.S. sailors. The inaugural ceremony for the new system will be attended by top U.S. and NATO military officials.

The Romania installation is the first land-based defensive missile launcher in Europe and will join other elements of the NATO defensive shield, including a command-and-control center at Ramstein Air Base, Germany, a radar installation in Turkey and four ships capable of identifying enemy missiles and firing their own SM-3s based in Rota, Spain.

The U.S. and NATO have continually stressed that the system is intended to defend Europe from Iran and its expanding arsenal. Tehran has continued to test-fire ballistic missiles following the internationally negotiated deal to limit its nuclear program.

But Russia has dismissed the justification.

"From the very outset we kept saying that in the opinion of our experts the deployment of an anti-missile defense poses a threat to Russia," Russian presidential spokesman Dmitry Peskov said, according to the Tass News Agency. "The question is not whether measures will be taken or not; measures are being taken to maintain Russia's security at the necessary level."

Russia believes the missile defense system breaches a 1987 agreement it signed with the U.S.

In October, at a meeting of the meeting of the Valdai International Discussion Club in Russia, Russian President Vladimir accused the U.S. of "lying" about a "hypothetical Iranian threat, which never existed" and called the system "an attempt to destroy the strategic balance."

At a Wednesday press conference in Romania, Deputy Assistant Secretary of State Frank Rose pushed back on Putin's perspective.

"Russia has repeatedly raised concerns that U.S. and NATO missile defenses are directed against Russia and represent a threat to its strategic nuclear deterrent," he said. "Nothing could be further from the truth."

He added that the "U.S. and NATO missile defense systems are directed against ballistic missile threats outside the Euro-Atlantic area. NATO and the United States have explained this to Russia many times over the years."

Heather Conley, the director of the Europe Program at the Center for Strategic and International Studies in Washington, told CNN that Russia has previously suggested that it could retaliate for the missile defense system by stationing S-300 surface-to-air missile systems in Crimea and Kaliningrad, its European enclave located between Poland and Lithuania.

Obama had previously drawn criticism from politicians in the U.S. and Europe for canceling the Bush-era plan to station land-based interceptors in Poland and the Czech Republic in 2009. Obama was further criticized for announcing the change on the day of the 70th anniversary of the Soviet Union's invasion of Poland during World War II.

Conley said that announcement would "go down in the history of poorly timed announcements."

Obama was also caught on an open mic in 2012 telling then-Russian President Dimitry Medvedev, that "After my election I have more flexibility," with regard to the U.S.-led NATO missile defense system in Europe.

Obama's posture made the Poles and Czechs "very concerned" that the entire missile defense project would be abandoned by his administration, according to Conley.

But, she said, "What they wound up getting with the current system was more robust than they had anticipated."

Conley said that the Obama administration might have switched gears on the Bush plan in part because it may have been trying to "buy time in order to make the case" to Russia that the new system was not directed against them.

She referred to that period as "the heady days of the 'Russian Reset' and New START treaty," an attempt by the newly inaugurated Obama to repair relations with Russia and sign a new arms reduction treaty -- and signal that the missile defense shield wasn't a threat.

But she added, "Despite an incredible amount of consultations with Russia, the Russians never bought the argument that the system was not directed at them."

Tensions between the U.S. and Russia have increased in recent years following the Russia's annexation of Crimea in 2014 and intervention in Eastern Ukraine.

In recent months, Russian military aircraft have flown within 50 feet of U.S. planes and ships, actions which Pentagon spokesman, Capt. Jeff Davis, said had "the potential to unnecessarily escalate tensions between the two countries."